High-Performance G-Dimer Acceptor-Based Flexible Organic Solar Cells Optimized by Temperature-Dependent Film Formation Process

Abstract

Giant Dimer (G-Dimer) acceptors have shown their promising ability in the fabrication of high-performance organic solar cells; however, a lack of investigation on the morphology optimization of donor and acceptor (D-A) blends essentially confines their potential application. Based on a typical Y6-analogues-based giant dimeric acceptor G-DimerC8C10, this study investigated the impact of varying processing temperatures on the behavior of the blends with donor PM6. The result indicated that as the processing temperature increased, the aggregation capacity of the donor is enhanced. This enhancement can be attributed to the reduced nucleation sites and the accelerated diffusion rate of PM6, which consequently resulted in forming nanofiber with larger diameters. Concurrently, the vertical phase distribution of the active layer is observed, with progressively ascended donor and descended acceptor due to the disparate drying times of the donor and the acceptor. The synergistic regulated vertical phase distribution and nanofiber morphology resulted in an optimized dissociation rate of excitons and an enhanced hole transport rate. Especially, the 1 cm² flexible device fabricated by slot-die coating achieves a record power conversion efficiency (PCE) of 14.38% at the optimized processing temperature (90 °C), which paved the way for future upscaling applications.